Insulated article



March 21, 1933. J. R. FOLEY INSULATED ARTICLE Filed Jan. 23, 1932 2Sheets-Sheet l .n ll? v March 21, 1933.

J. R. FOLEY INSULATED ARTICLE Filed Jan. 23, 1932 2 Sheets-Sheet 2gwumdoz Patented Mar. 21 1933 PATENT; OFFICEv JOHN RUSSELL FOLEY, OF NEWYORK, N. Y.

INSULATED ARTICLE Application filed January 23, 1932. Serial No.588,425.

This invention relates to improvements in methods for insulating handtools, such as screw drivers, pliers, hack saws, track lifting irons,crow bars, wrenches, etc, and to improved hand tools or the like forgeneral use and practice in connection with high voltage electricalequipment and the like.

Heretofore it has been proposed to insulate tools and the like employedby operators working about high voltage electric current, but suchinsulation will not withstand the tests required by the specificationsfor such tools. For example, one specification requires:

1. Dielectric strength test.-Samples shall not be broken downelectrically by a voltage up to 3000 volts.

2. Impact tcst.Samples shall be tested allowing a three pound weightwith a 90 sharp V-edge to fall on the insulation. The

insulation shall not crack internally or externally, chip, peel, orpuncture at a voltage of 110 volts applied during this test when theabove Weight falls freely a distance of 2 feet 5 or less.

3. Torsion strength test-Samples shall be tested in accordance with thetest as described in the U. S. Navy specification for screwdrivers, No.41S27 a, dated September 1, 1927. This requires a torsion test betweenthe tip of the blade and the handle as follows:

3 inches 50 in lbs. 4. inches 75 in lbs. 6 inches 100 in lbs. 8 inches200 in lbs.

The screw drivers are to withstand the above tests without anyindication of weakness.

It is the primary purpose of the present invention to provide insulatedarticles capable of meeting or passing such specifications, and While Ihave found substantially non-inflammable cellulose plastics particularlyusefulfor this purpose, I prefer to employ a base consisting ofcellulose acetate. When cellulose is treated with acetic anhydride inthe presence of a trace of concentrated sulfuric acid, the cellulose ischanged into the triacetate. o.H.o.(0o.oH This is readily soluble inacetone, alcohol, ethyl lactate, acetylene tetrachloride, methylcellosolve (ethylene glycol mono-methyl ether) and other plastecelesolvents. The acetate is deposited from solution in the form of a toughfilm as solvent evaporates. This film may be dyed any color or made intoany desired thickness, but the time necessary for the solvent to becompletely evaporated is quite lengthy in the greater thickness. 5

In accordance with the present invention, the article to be insulated isdipped to any desired extent into such a solution, but as the solutionitself will not adhere to metal except by contraction, I prefer to coverthe metal portion of the tool or the like during the dipping treatment,with a lamination of linen taip-e or the like which may be wound into pace.

Another object of the invention is to label lo the tool or the likewhile insulating the same, in such manner that the label cannot bedestroyed without mutilating the insulation.

With the foregoing objects outlined and with other objects in view whichwill .appear as the description proceeds, the invention consists in thenovel features hereinafter described in detail, illustrated in theaccompanying drawings, and more particularly pointed out in the appendedclaims.

In the drawings,

Fig. 1 is an elevation of an ordinary screw driver after a single coatof the triacetate has been placed on the same by a dipping operation,such insulation being shown in section. V

Fig. 2 is a similar view after the second dipping.

Fig. 3 is an elevation of the partially insulated tool after anidentification label has been placed on it.

Fig. 4 is a View like Fig. 2 after the label has been placed in positionand the tool has been subjected to a third dipping.

Fig. 5 is an elevation of the tool shown in Fig. 4, after the shankportion of the screw driver has been wrapped with linen tape or thelike.

Fig. 6 is a similar view after the taped portion has been subjected to asingle dip rung.

L Fig. 7 is a like view after the taped portion has been subjected to asecond dipping.

Fig. 8 is a transverse sectional view of the tool on the line 8-8 ofFig. 1.

Figs. 9 and 10 are similar views taken respectively on the lines 99, andl10 of Figs. 2 and a.

Fig. 11 is an elevation of the finished tool.

12 is a longitudinal sectional view of the same on the line l2l2 of Fig.ll.

Figs. 13, la and 15 are sectional views taken respectively on the linesl313, lt-lt and l-15 of Fig. 11.

Referring to the drawings, it will be noted Figs. 1 to inclusive thatthe thickness of the films of insulation is greatly exaggerated tofacilitate illustration, and while the invention is illustrated inconnection with a screw driver, it will be noted that it is applicableto all hand tools or the like in general use and practice with referenceto high voltage electrical equipment or the like.

in practicing the invention, preferably use two solutions or"triacetate, comprising a solvent which may readily evaporate. Une ofthese solutions is of maximum density, and the other of less density. Inproceeding, an ordinary screw driver 16 or like is dipped in thesolution of maximum density to cover the handle If? and all of the metalshank 18, with the exception of its tip 19,

with a film or coat 20 of such insulating material. l Vhen the tool isremoved from the solution, the coat is permitted to dry for period offrom 15 to 90 minutes. Then the -tool again dipped in the solution ofmaxidensity to provide it with a second coat oriilm 21 of the insulatingmaterial. Before this coat dries, a label 22 is placed on the handleportion by'superposing the label on the second coat insulation.

in makinga suitable label, I paste letters 23 on sheet of hardtriacetate and coat over these letters with a thin film of one of thetriacetate solutions. it is preferred to use a label 22 off a colorcontrasting to the color of the films or coats, and as a single coat ofthe material is more or less transparent, it

will be understood that such label will be I displayed even arter thetool has been dipped the third time into this solution of less densityto form the film or coat 2t.

Instead of employing a label of the above type, l may use a printedlabel on which the lettering will be of a color contrasting to thebackground. Such background may be gummed paper which will be pastedover the tool after the second dipping, and of course, the label will becoated and transparently covered during the third dipping.

After this is permitted to dry for a period oi about third coat isapplied, the tool twenty-four hours, and this completes the insulationof the handle.

However, as the coats on the metal shank 18 will not tenaciously adhereto the latter, 1 Wrap the coated shank portion of the tool with a stripof, linen tape 25 or the like, as shown in Fig. 5, and this acts as anabsorbent binding sleeve or annular lamination which prevents theinsulating material from peeling oil or cracking.

In the event of the handle itself being of an insulated material throughwhich no metal projections are visible, it is not essential to carry thebinding tape over so as to tape the handle. It only becomes necessary totape the handle in such cases where metal portions of the tool areexposed at the handle surface. This condition exists in various types oftools, and it results in increasing the torsion I strength of the handleto prevent it irom turning on the metal shank. prevent such turning doesnot always extend, however, to the surface of the handle, and in suchcase, it is unnecessary to extend the taping over the handle. it will beunderstood, however, that where metal surfaces are exposed at thehandle, handle as Well as the metal shank.

After the tool has been taped, the taped portion of the tool is dippedinto the solution of maximum density to cover this portion with a fourthfilm or coat 26 of triacetate solution, and then this fourth coat ispermitted to dry from about 15 to 90 minutes. Afterwards, the tapedportion of the tool is again dipped in the solution of less density toprovide a fifth coat 27, and then this coat is permitted to dry for aperiod of about twenty-four hours.

Manifestly, the invention is applicable to tools having handles ofvarious materials, and in some instances, l have applied the insulationto tools having handles made up wholly or in part of plastic woods ofthe kind which can now be purchased on the open market. Such plasticwoods have a dielectric strength of their own, and of course, when linsulate such a tool, the dielectric strength of the handle of the toolis augmented.

As a final operation, the outer surface Provision to of the insulatingmaterial is dipped in a solvent such as acetone, andis rubbed down bythe bare hands to smooth the outer surface of the insulation and toeliminate wrinkles and the like.

As illustrated in Figs. 11 to 15 inclusive, it will be understood thatwhen the tool is finished, the handle will be covered with a homogeneousshell 28 of the insulating material which will only be interrupted bythe label 29, while the metal shank will be covcred with an inner shell30 of insulating materlal, an ntermediate layer or lamination ill Ipropose to tape the p 31 of absorbent shock absorbing tape or the like,and an outer shell 32 of the insulating material.

Such a tool will meet with the specifications heretofore mentioned, andthe insulation has sufficient toughness to withstand the rough usage towhich such tools are subjected throughout the life of the tool.

While I prefer to use a protective coating containing cellulose acetate,it will be evident that other similar substances may be employed, suchfor instance, as henolic condensation products, which can b a liquidcondition, and which may subsequently set into a hard condition on thearticle.

From the foregoing it is believed that construction and advantages of myinvention may be readily understood by those skilled in the art, and itis apparent that changes may be made in the details disclosed, withoutdeparting from the spirit of the invention, as expressed in the claims.

What I claim and desire to secure ters Patent is:

1. A tool or the like, coated with electric insulation material havingthe dielectric characteristic of cellulose acetate, and a label embeddedin said material, covered over by the material and visible through thelatter.

2. A screw driver comprising a handle and a metal shank, said screwdriver being entirely covered with the exception of its tip with a shellof insulating material having by Leta the dielectric characteristics ofcellulose acetate, and a label incorporated in said insulating material,covered by the latter and visible through said insulating material.

3. A conventional tool coated with electric insulating material,consisting mainly of cellulose acetate, and a tubular lamination ofabsorbent shock absorbing material embedded within said insulatingmaterial and spaced from the metal of the tool by said insulatingmaterial.

4. A conventional screw driver comprising a handle and a metal shankrigidly united with the same, said screw driver being entirely coveredwith the exception of its tip with a ing mainly of cellulose acetate,and a tubular lamination of textile shock absorbing material embeddedwithin said insulating material and spaced from the metal of the tool bysaid insulating material.

' 5. A conventional screw driver comprising a handle and a metal shankrigidly united with the same, said screw driver being entirely coveredwith the exception of its tip with a shell of insulating materialconsisting main- I 1y of cellulose acetate, and a tube of absorbentshock absorbing material arranged within 'the portion of the insulatingmaterial which surrounds said shank, and spaced from said e applied inshell of insulating material consistshank and from the exterior surfaceof the lnsiilating material by said insulating mater1a In testimonywhereof, I have signed this specification.

JOHN RUSSELL FOLEY.

